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Biological Screening Workshop

Other Body Fluids and Tissues



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Vaginal Secretions

Biological Screening Workshop: Other Body Fluids and Tissues


Vaginal Secretions

• Vaginal secretions are a complex mixture of cells and secretions

• There is no confirmatory test to identify vaginal secretions

• Several screening tests based on microscopy have been proposed

3Biological Screening Workshop: Other Body Fluids and Tissues


Vaginal Secretions

• Vaginal epithelial cells are large, and many contain glycogen (a polysaccharide) which can be demonstrated by staining with iodine in the form of a solution or exposing to iodine vapor

• The presence of glycogenated cells is variable depending on the stage of the estrous cycle

• Glycogenated cells can be found in other body secretions (i.e. oral, anal)



Lugol’s Staining

Epithelial cells stained chocolate brown

Gold/yellow stained epithelial cells



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Fecal Material



Fecal Material

• Feces are food residues passed after completion of travel through the digestive system

• Has a characteristic odor mainly due to skatole, an organic compound that occurs naturally in feces



Fecal Material

• Microscopy− Microscopy has been used to identify fecal material

• Looking for undigested residues of food material

• Chemical Tests− Detection of urobilinogen, a bile pigment excreted in feces, which may be detected using its fluorescent reaction to Edelman’s reagent



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Urine



Urine

• No confirmatory tests for the presence of urine

• Urine stains fluorescent under ultraviolet light− This can be useful for locating stains prior to chemical testing

• Has a characteristic odor



Urine

• Contains a large amount of urea, a chemical byproduct of normal metabolic processes in the body− Identification of high levels of urea can serve as a screening test for urine in fluids or stains

− Perspiration can give reactions similar to urine



Urea – Litmus Paper Test

• Litmus paper test for the detection of ammonia

• Relies on the indirect identification of urea by reacting a test sample with urease to generate ammonia from the urea

• Litmus paper is used to detect the ammonia

Urea + H2O ↔ CO2 + 2NH3



Urea – Litmus Paper Test

• A known urine sample and a blank are tested as a positive and negative control

• A substrate control may be tested, as needed



Urea – Nitrogen Tube Test

• Relies on the indirect identification of urea by reacting a test sample with urease to generate ammonia from the urea

• Ammonia is subsequently identified by the production of a deep blue‐colored solution

Urea + H2O ↔ CO2 + 2NH3



Urea – Nitrogen Tube Test –How to Perform

Sample Expected Results

Negative Control No color

Standard Deep blue color

Positive Control Deep blue color

Substrate Control No color

Question Sample (without urease) No color



Creatinine

• Jaffe Test− One of the oldest tests for the detection of creatinine‐1886

− Creatinine forms a red compound with picric acid (Jaffe test)



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Hair



Hair

• Composed of cylindrical structures or shafts made up of tightly compacted cells that grow from follicles

• Diameter ranges from 15 to 120 µm− Depends on type of hair and body region

• Root material can be used for nuclear DNA testing

• Shaft material can be used for mtDNA testing



Hair

• Human hairs are distinguishable from hairs of other mammals

− Human hairs are generally consistent in color and pigmentation throughout the length of the hair shaft

− Animal hairs may exhibit radical color changes in a short distance, called banding



Hair

• The medulla, when present in human hairs, is amorphous in appearance, and the width is generally less than one‐third the overall diameter of the hair shaft

• The medulla in animal hairs is normally continuous and structured and generally occupies an area of greater than one‐third the overall diameter of the hair shaft



Hair

• Structure

• Three cell types− Outer cuticle

− Central cortex

− Central medulla



Hair

• In some instances human hairs can be classified by racial origin such as:− Caucasian (European origin)

− Negroid (African origin)

− Mongoloid (Asian origin)

• In some instances the region of the body where a hair originated can be determined by its gross appearance and microscopic characteristics



Hair

• The length and color can be determined

• It can also be determined whether the hair was forcibly removed, damaged by burning or crushing, or artificially treated by dyeing or bleaching



Hair

• The growth phase of the hair is important in determining whether the root is suitable for nuclear DNA analysis testing

• Growth Cycles− Anagen phase

− Catagen phase

− Telogen phase



Hair – Anagen Phase

• Active hair growth

• Contains nucleated cells in the root and in the surrounding sheath material

• Generally suitable for nuclear DNA analysis



Hair – Anagen Hair



Hair – Catagen Phase

• Transitional phase after active hair growth, cell division stops

• Characteristic club appearance of root

• May be suitable for nuclear DNA analysis



Hair – Catagen Hair



Hair – Telogen Phase

• Follows transitional phase‐growth ceases

• Shedding phase

• Telogen hairs without follicular tissue may not be amenable to nuclear DNA analysis because of the lack of nucleated cells− May contain sufficient mitochondrial DNA in their roots and hair shafts for analysis



Hair – Telogen Hair



Hair – Basic Evaluation Steps

1. Determine if the sample is a hair.

2. Determine if the hair is of human origin.

3. Determine if the hair has root material that is suitable for nuclear DNA analysis (characteristic of a particular growth phase).− If not suitable for nuclear DNA analysis, determine if

the hair is sufficient in size for mtDNA analysis (two to three centimeters)



Hair

• DNA analysis of hair is a destructive technique and results in the consumption of portions of the hair− Hair characteristics, such as color, length, shape, and texture should be noted in the case file for future reference prior to DNA analysis• Notes and digital images



Questions?


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